Low-Cost Calibration MOS Gas Sensor for Measuring SO2 Pollutants in Ambient Air

Abstract

Air pollution has evolved into a global issue that necessitates immediate and accurate pollution control. The usage of the Metal Oxide Semiconductor (MOS) sensor as a monitoring system for air pollution levels is one possible answer to this challenge. The MQ-136 sensor is calibrated using standard SO2 (0, 5, 10, 20, 30, 40, 50, 60, 70) ppm as the test gas in this study. To collect the sensor output signal, a variety of equipment was created, including a gas test box, a voltage divider, and follower circuit, and a gas flow control unit operated by a microcontroller. The test gas can be pumped into the test box at a constant rate of 1.0 L.min-1 by the apparatus. To evaluate a significant difference (= 0.05), an analysis of variance was performed on the response signal generated by a series of sensors due to the concentration of the test gas. To examine the correlation between the sensor response signal and the test gas concentration treatment, as well as the sensor performance, linear regression analysis was used. The ANOVA results demonstrate no significant differences amongst the sensors, indicating that they all follow the same routine. Furthermore, ANOVA analysis reveals that the sensors respond differently at each level of SO2 concentration. According to linear regression, the relationship between gas concentration and sensor-1, sensor-2, and sensor-3 output signals is reflected by coefficients of determination of 0.94, 0.91, and 0.93, respectively.